// UserAgentUtil.javapackage com.yaojianfeng.doubancrawler.config;import java.util.Random;public class UserAgentUtil {    private static final String[] USER_AGENTS = {            "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.124 " +                    "Safari/537.36",            "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472" +                    ".124 Safari/537.36",            "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.124 Safari/537.36"    };    public static String randomUA() {        Random rand = new Random();        return USER_AGENTS[rand.nextInt(USER_AGENTS.length)];    }}